Bump urllib3 from 1.24.2 to 1.25.6 (#6)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.24.2 to 1.25.6.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/master/CHANGES.rst)
- [Commits](urllib3/urllib3@1.24.2...1.25.6)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -58,7 +58,7 @@ six==1.10.0
 SQLAlchemy==1.1.11
 SQLAlchemy-Utils==0.32.16
 typing==3.5.3.0
-urllib3==1.24.2
+urllib3==1.25.6
 validators==0.12.0
 Werkzeug==0.15.3
 wrapt==1.10.11